GSoC 2017 video stuck issue fixed

After last week’s work the decoder is now able to play videos normally. The video getting stuck at the end was fixed along with other improvements that I talk about below.

Signalling EOS

Earlier I had left signalling end of stream for later to do. This only needed to propagate the flag on the ouput buffer as

p_prc->p_outhdr_->nFlags |= OMX_BUFFERFLAG_EOS;

But it was a little tricky because of the sliding window. The decoder should not release the output buffer before all the buffers in the window have been decoded when EOS is reached. https://github.com/gpalsingh/mesa/commit/69985535972593a4ccd9630efcb3106f8737a8d2 fixed that issue.

That along with the error correction in https://github.com/gpalsingh/mesa/commit/97995b031149ad7d709aca908fd1d263579c1560 made the video close smoothly on ending.

No more dependence on gst-omx for port configuration

For development earlier we were using workarounds for nStride other parameters. Also the component depended on the client to update the corressponding ports. With the patch in https://bugzilla.gnome.org/show_bug.cgi?id=783976 that behaviour was changed. Removing the workaround and using this patch the component stopped working. It was because the outport needed to be enabled first by the component before sending any output. https://github.com/gpalsingh/mesa/commit/32f535834fb7c11095830e49380a3612dc6e8563 made it able to start the decoding process but later on I was again faced another problem.

The decoder assumed that the input buffer is cleared after it’s read. But now in case the out port is disabled the input buffer can’t be cleared. In that case the decoder needs to wait until the right time to release the claimed buffer. https://github.com/gpalsingh/mesa/commit/868577f36ebb6435615938ccae19e90abee237bb fixed that issue by adding checks in decode_frame and get_input_buffer and separating the buffer shifting logic from decode_frame.

Reading stream parameters from headers In https://github.com/gpalsingh/mesa/commit/32f535834fb7c11095830e49380a3612dc6e8563 the decoder sends a “fake” event to just enable the out port as

    tiz_srv_issue_event ((OMX_PTR) p_prc, OMX_EventPortSettingsChanged, OMX_VID_DEC_AVC_OUTPUT_PORT_INDEX, OMX_IndexParamPortDefinition, /* the index of the struct that has been modififed */ NULL);

while reading the header. https://github.com/gpalsingh/mesa/commit/0d79ca5b760ee4b9c3655c94a56ef75065a329fa changes this by actually reading the values and updating them. This also removed dependency on the h264d_SetParameter workaround which was removed.

Moving on

The component works fine with normal streams but fails with streams which change parameters. Also while seeking there is a possibility that the out port will fail to flush and a timeout will occur. The major goal now is to add support for OMX_UseEGLImage which allows faster decoding process.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s